1. Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly, to an LCD comprising color filters with recess structures.
2. Description of the Prior Art
Due to low prices and high quality of liquid crystal displays (LCDs), the LCD is widely applied in notebooks, PDAs, mobile phones, and so on.
Please refer to FIG. 1. FIG. 1 shows a sectional view of a conventional color LCD 11. The color LCD 11 comprises a lower glass substrate 9, an upper glass substrate 2 positioned parallel to and above the lower glass substrate 9, and a plurality of pixel units (not shown in FIG. 1) positioned between the lower glass substrate 9 and the upper glass substrate 2, each of the pixel units including a red color filter 3R, a green color filter 3G, or a blue color filter 3B. An inner surface of the upper glass substrate 2 includes an upper transparent electrode 4, and an inner surface of the lower glass substrate 9 includes a lower transparent electrode 8 and a plurality of thin film transistors (not shown in FIG. 1) for controlling the pixel units. Furthermore, a liquid crystal layer 6 is positioned between the upper glass substrate 2 and the lower glass substrate 9, and an exposed portion of an outer surface of the upper glass substrate 2 and an exposed portion of another surface of the lower glass substrate 9 respectively include an upper polarizer 1 and a lower polarizer 10. The above-mentioned color LCD 11 is a transmissive color LCD. A reflective color LCD similar to the transmissive color LCD further comprises a reflection layer (not shown in FIG. 1) positioned between the color filters 3R, 3G, 3B and the lower glass substrate 9. Additionally, a transflective color LCD comprises a diffusion layer (not shown in FIG. 1) positioned between the upper polarizer 1 and the lower polarizer 10.
Since the transmissive LCD is a passive luminous device, a backlight source (not shown in FIG. 1) positioned behind the lower glass substrate 9 is required for the color LCD 11. A white light is radiated from the backlight source and passes through the color filters 3R, 3G, 3B so as to enable each of the pixel units to respectively display a red light, a green light, and a blue light. However, only portions of the white light with specific wavelengths can pass through the color filters. For the reflective color LCD, the white light radiated from the backlight source has to pass through the color filters and reach a surface of the reflection layer, then the light is reflected by the reflection layer and again passes through the color filters for respectively displaying a red light, a green light, and a blue light. Consequently, comparing to the transmissive color LCD, the color deepness of the reflective color LCD is greater, and the problem of the reflective color LCD having insufficient brightness is more serious.
For solving the above-mentioned problems, a conventional color LCD 15 comprises light transmitting holes 18 respectively formed in the color filters 16R, 16G, 16B of each pixel unit, as shown in FIG. 2. Therefore, the transmittance of the color filters 16R, 16G, 16B can be increased for improving a brightness of a transmissive color LCD or a reflective color LCD, and a color deepness of the transmissive color LCD or the reflective color LCD is also regulated. However, the method of forming holes 18 in the color filters 16R, 16G, 16B results in a non-uniform cell gap 19, and an overcoating layer 17 is required for covering the color filters 16R, 16G, 16B. Because the gap 19 caused by the formation of the holes 18 is great, the overcoating layer 17 formed for planarization is not so effective, and a stability and a quality of the LCD 15 is reduced.